Best size for full-range driver?

[planet10]

Originally Posted by sprinter

Is it strong enough to handle a large room, such as 30' x 18'?

So much depends on how loud you have to have it.

My room is largish (bigger than yours). I think the sweet spot is 4-5". No matter the size of the FR, it will really need big helper woofer(s) to get real bass impact.

You can get pretty low (and with finesse) with some of the FRs in this size (the CSS EL70 is a real stunner in this department), but they just can;t move the air needed for lots of impact. Besides, freeing the FR of low bass, gives big imprvements in mirange & HF finese.

dave

[picowallspeaker]

Whoa Scott !!
I wasn't clear -it should be noted that I'm quite a profane - I was referring more to the relation between cone diameter and directivity towards frequency .
As this implies also bandwidth and positioning of the speakers ...
...given the same motor , a lighter cone -and possibly little to reduce cone diaphgram non-linearities (break-ups)- has more speed ,thus being able to 'throw' sound to a longer distance .

[pengesluk]

Originally Posted by Scottmoose

I'm afraid not. Mass affects efficiency, but it does not impact on transient response. Transient response is inherently linked to bandwidth covered & the acceleration of the powertrain is proportional only to the amount of current in the voicecoil. The equation B*L*i / Mms clearly demonstrates this, where B = magnetic strength in the Vc gap, L = length of the VC in the VC gap, i = current in the VC, and Mms = moving mass of the powertrain (all in SI units, naturally). Dan Wiggins's did a short writeup on the subject a few years ago: http://www.adireaudio.com/Files/WooferSpeed.pdf

Absolutely true, and let's not forget the inductance, Le, . Has a major impact on dynamics.

A good example, the TAD midrange 12" (!!) TM-1201 with Le= 0,68, BL=26,
mms = a whoppin' 60 grams, BUT the motor force is a brutal 14.500 G.

This driver is as "fast" and dynamic as it gets before moving to horns and CD's.

Rimshots etc. that will throw you out of your chair!

[pengesluk]

Concerning size of the optimal FR driver my absolute preferred would have to be 8". At least if your room has a fairly nice size, let's say 1.200 cu.ft. or more.

There is a reason for so many manufacturers offering this particular size of drivers, and YES, there are exeptions of course, but in general an 8" is quite capable and have compromises within reasonable values.

[picowallspeaker]

Originally Posted by picowallspeaker

I was referring more to the relation between cone diameter and directivity towards frequency

I can't believe those things can happily live in a single driver . It's just physics.
Phase shifts inherently happen when a speaker is requested to reproduce full band . Oh sorry should I be addressed as a bad mentor being in the FR forum ..!?!

[planet10]

Originally Posted by pengesluk

There is a reason for so many manufacturers offering this particular size of drivers

And i think too, some of that testoserone driven "mine is bigger than yours"

I've yet to hear a big driver (8") that doesn't give up midrange finese and downward dynamic range.

dave

[pengesluk]

There is nothing "big" about an 8" speaker...??

[hm]

"There is nothing "big" about an 8" speaker...??"
thats right my 39 years experience shows for a fullrange
8" is a maximum which make sence by membran area, beaming, membran weight.

[norman bates]

In a room that big , I'd want 8" plus bass support, but then you lose dispersion. But you should have enough dispersion for a couch at 12' away.

An 8" starts losing highs around 2khz when seated off axis.

Playing with a tannoy arena loudspeaker (6.5" with ict tweet at center), I found 200hz worked well (24db/octave), 500hz was great for flattening volume, but 200hz was the best for keeping all the voice in the full range driver.

Dual 4", cone area near 120cm2 close to a 6" (listening to a single speaker with zero bass support) sounds congested 12' away at medium volume (listening to Blues Traveler). Now 4 x 4" (equal to an 8" cone area), that had enough area to satisfy me, but not keep me satisfied. Sitting arms length from the dual 4", there was bass. Move further away, there was no bass.

It all depends on dispersion you want, volume you listen at, music, and how far away you sit.

Norman

[hm]

Hello,
3,5 m listening distance is not a large room, every 20 sqm room has this distance,
here is a large room with large bass horn